<template>
  <div>
    <div class="goods">
      <div class="menu-wrapper" ref="menuWrapper">
        <ul>
          <li class="menu-item" v-for="(good, index) in goods" :key="index" style="cursor: pointer;"
              :class="{current: index===currentIndex}" @click="clickMenuItem(index)">
            <span class="text bottom-border-1px">
              <img class="icon" :src="good.icon" v-if="good.icon">
              {{good.name}}
            </span>
          </li>
        </ul>
      </div>
      <div class="foods-wrapper" ref="foodsWrapper">
        <ul>
          <li class="food-list-hook" v-for="(good, index) in goods" :key="index">
            <h1 class="title">{{good.name}}</h1>
            <ul>
              <li class="food-item bottom-border-1px" v-for="(food, index) in good.foods" :key="index" @click="showFood(food)" style="cursor: pointer;">
                <div class="icon">
                  <img width="57" height="57" :src="food.icon">
                </div>
                <div class="content">
                  <h2 class="name">{{food.name}}</h2>
                  <p class="desc">{{food.description}}</p>
                  <div class="extra">
                    <span class="count">月售 {{food.sellCount}} 份</span>
                    <span>好评率 {{food.rating}}%</span></div>
                  <div class="price">
                    <span class="now">￥{{food.price}}</span>
                    <span class="old" v-if="food.old">￥{{food.old}}</span>
                  </div>
                  <div class="cartcontrol-wrapper">
                    <cart-control :food="food"/>
                  </div>
                </div>
              </li>
            </ul>
          </li>
        </ul>
      </div>
      <shop-cart/>
    </div>
    <food :food="food" ref="food"/>
  </div>
</template>

<script>
  import {mapState} from 'vuex'
  import BScroll from 'better-scroll'
  import CartControl from '../../../components/CartControl/CartControl'
  import Food from '../../../components/Food/Food'
  import ShopCart from '../../../components/ShopCart/ShopCart'

  export default {
    name: "ShopGoods",
    data() {
      return {
        scrollY: 0, //右侧滑动的Y轴坐标（滑动过程时实时变化）
        tops: [], //所有右侧分类li的top组成的数组（列表第一次显示后就不会变化）
        food: {}, //点击要显示的food
      }
    },
    components: {
      CartControl,
      Food,
      ShopCart,
    },
    computed: {
      ...mapState(['goods']),
      // 计算得到当前分类的下标
      currentIndex() {
        // 得到条件数据
        const {scrollY, tops} = this;
        // 根据条件计算产生一个结果
        const index = tops.findIndex((top, index) => {
          // 当前的scrollY >= top，并且scrollY < 下一个top
          return scrollY >= top && scrollY < tops[index + 1];
        });
        // 返回结果
        return index;
      }
    },
    methods: {
      // 初始化滚动条
      _initScroll() {
        // 列表显示之后创建
        new BScroll('.menu-wrapper', {
          click: true,
        });
        this.foodsScroll = new BScroll('.foods-wrapper', {
          probeType: 2, // 手指滑动(惯性滑动和编码滑动不监视)
          click: true,
        });
        // 给右侧列表绑定scroll监听
        this.foodsScroll.on('scroll', (pox) => {
          this.scrollY = Math.abs(pox.y);
        });
        // 给右侧列表绑定scrollEnd结束监听
        this.foodsScroll.on('scrollEnd', (pox) => {
          this.scrollY = Math.abs(pox.y);
        });
      },
      // 初始化tops
      _initTpos() {
        // 1.初始化tops数组
        const tops = [];
        let top = 0;
        tops.push(top);
        // 2.收集，找到所有分类的li
        const lis = this.$refs.foodsWrapper.getElementsByClassName('food-list-hook');
        Array.prototype.slice.call(lis).forEach(li => {
          top += li.clientHeight;
          tops.push(top);
        })
        // 3.更新数据
        this.tops = tops;
      },
      // 点击分类，并滚动到指定的坐标
      clickMenuItem(index) {
        // 得到滚动目标坐标
        const top = this.tops[index];
        // 更新目标 scrollY 值
        this.scrollY = top;
        // 平滑滚动到指定位置
        this.foodsScroll.scrollTo(0, -top, 300);
      },
      // 显示点击的food
      showFood(food){
        // 设置food
        this.food = food;
        // 显示food（父组件调用子组件对象的方法）
        this.$refs.food.toggleShow();
      }
    },
    mounted() {
      this.$store.dispatch('getShopGoods', () => {
        this.$nextTick(() => {
          this._initScroll();
          this._initTpos();
        });
      });
    },
  }
</script>

<style lang="stylus" rel="stylesheet/stylus" scoped>
  @import "../../../common/stylus/mixins.styl"
  .goods
    display: flex
    position: absolute
    top: 195px
    bottom: 46px
    width: 100%
    background: #fff;
    overflow: hidden
    .menu-wrapper
      flex: 0 0 80px
      width: 80px
      background: #f3f5f7
      .menu-item
        display: table
        height: 54px
        width: 56px
        padding: 0 12px
        line-height: 14px
        &.current
          position: relative
          z-index: 10
          margin-top: -1px
          background: #fff
          color: $green
          font-weight: 700
          .text
            border-none()
        .icon
          display: inline-block
          vertical-align: top
          width: 12px
          height: 12px
          margin-right: 2px
          background-size: 12px 12px
          background-repeat: no-repeat
        .text
          display: table-cell
          width: 56px
          vertical-align: middle
          bottom-border-1px(rgba(7, 17, 27, 0.1))
          font-size: 12px
    .foods-wrapper
      flex: 1
      .title
        padding-left: 14px
        height: 26px
        line-height: 26px
        border-left: 2px solid #d9dde1
        font-size: 12px
        color: rgb(147, 153, 159)
        background: #f3f5f7
      .food-item
        display: flex
        margin: 18px
        padding-bottom: 18px
        bottom-border-1px(rgba(7, 17, 27, 0.1))
        &:last-child
          border-none()
          margin-bottom: 0
        .icon
          flex: 0 0 57px
          margin-right: 10px
        .content
          flex: 1
          .name
            margin: 2px 0 8px 0
            height: 14px
            line-height: 14px
            font-size: 14px
            color: rgb(7, 17, 27)
          .desc, .extra
            line-height: 10px
            font-size: 10px
            color: rgb(147, 153, 159)
          .desc
            line-height: 12px
            margin-bottom: 8px
          .extra
            .count
              margin-right: 12px
          .price
            font-weight: 700
            line-height: 24px
            .now
              margin-right: 8px
              font-size: 14px
              color: rgb(240, 20, 20)
            .old
              text-decoration: line-through
              font-size: 10px
              color: rgb(147, 153, 159)
          .cartcontrol-wrapper
            position: absolute
            right: 0
            bottom: 12px
</style>
